Circular slide rule



Sept. 1., 1970 J. B. R. LEFEVIBVRE 3,526,357

CIRCULAR SLIDE RULE Filed July 16, 1968 ZEs-EE INVENTOR Joseph Bernard Rg olre LE F E BVRE QW W AGENT United States Patent U.S. Cl. 235-795 3 Claims ABSTRACT OF THE DISCLOSURE A circular slide rule consisting of a cylindrical body having an axial extension of smaller diameter, on which are mounted in end-to-end relation two cylinders: the one at the end of the extension being secured to said extension and the other one being free to rotate around the extension, and including means to rotate said lastnamed cylinder operable from the free end of the ex-- tension, so as to angularly adjust the position of the intermediate cylinder relative to the cylindrical body and endmost cylinder, so as to properly align circularly disposed scales inscribed on the cylindrical body and two cylinders.

SUMMARY OF THE INVENTION One cylinder has an extension extending in the axial direction out of one end. Second and third hollow cylinders extend over the extension end to end. The second cylinder is rotatable therearound, while the third cylinder is secured to the extension. A cylindrical cursor rotatably surrounds the three cylinders. Means are provided for rotating the second cylinder from one end of the extension. Each cylinder carries circularly disposed scales on its outer periphery. Relative manual rotation of the second cylinder with the help of the cursor carries out the desired calculations. The scales are those found on a conventional rectilinear slide rule.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side elevation of the circular slide rule of the invention;

FIG. 2 is a longitudinal section, taken along, line 2--2 of FIG.

FIG. 3 is an end elevation of the bevel wheel;

FIGS. 4, 5, and 6 are cross-sections taken along lines 4-4, 55, and 6-6 respectively of FIG. 2

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIGS. 1 to 6, a first cylinder 10 has a raised shoulder 44 at one end and an axial extension 10A at the other end, said extension being cylindrical and of smaller diameter. An extension piece 10B is glued or cemented to extension 10A and a piece 10C is glued on top of part 10B. Parts 10B and 10C form a body of square cross-section, as' shown in FIG. 5. Parts 10A and 10C are separated by a recess 40, in which is disposed a bevel rubber or plastic wheel 18 secured by setscrew 20 on a rod 26 and held in engagement with the bevel edge 16 of a cylinder or sleeve 12 by a leaf spring 24. Rod 26 extends through a bore 42, made in part 10C, and an operating wheel 32 is secured thereto by a setscrew 34, wheel 32 being at the end of the body of the slide rule.

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Thus, manual rotation of wheel 32 causes rotation of sleeve or hollow cylinder 12 with respect to body 10, 10A, 10B, and 100. A hollow cylinder 14 having a square longitudinal bore is fitted on parts 10B and 10C and secured thereto by setscrews 28. Hollo'w cylinders or sleeves 12 and 14 abut each other and conceal bevel wheel 18 at their junction. Sleeve 14 has a shoulder 44A of enlarged diameter at its outer end. The outer surfaces of part 10, sleeve 12 and sleeve 14 carry circularly disposed scales as depicted by scales K and A on part 10, scales B, C, C1, and S on cylinder 12 and Scale D on cylinder 14, as shown in FIG. 1. The scales are covered by a manually rotatable cylindrical cursor 22 having at least one longitudinal hair line 23. As will be obvious, the last graduation of a scale is coincident with the first graduation of the same scale, contrary to rectilinear slide rules.

Calculations are carried out in the same manner as with a conventional rectilinear slide rule by selective relative rotation of cylinder 12 driven by the bevel wheel 18, which is rotated by manually-operated wheel 32.

For instance, to multiply 2 by sine 40 by 4 one may proceed as follows:

The body of the slide rule is held with one hand at shoulder 44; graduation zero of scale S is brought opposite graduation 2 of scale D by rotating wheel 32; and the cursor 22 manually operated to bring the hair line of the graduation 40 of scale S. The resulting reading is 1.285.

Cylinder 12 is rotated to bring graduation 1 of scale C opposite reading 1.285 of scale D. Hair line 23 is brought on graduation 4 of scale D and the second power of 4 is read as 16 on scale A. The hair line 23 is brought over 16 of scale C of cylinder 12 and the answer, namely 20.56, is read on scale D.

Having thus described this invention, what is asserted as new is:

1. A cylindrical slide rule comprising: a first cylinder having an outer surface carrying mathematical scales and provided with an axial extension of reduced diameter; a second hollow cylinder having an outer scale carrying surface and disposed rotatably about a portion of said extension adjacent the first cylinder, one end of the second cylinder being disposed adjacent the extension supporting end of the first cylinder; and a third hollow cylinder having an outer scale carrying surface and disposed about another portion of said extension and secured to the latter adjacent the second cylinder, one end of the third cylinder being disposed adjacent the other end of the second cylinder, and wherein said extension is provided with a recess located below the abutting ends of said second and third cylinders, further provided with means communicating with said recess and engageable with said second cylinder for rotating said second cylinder relative to said first and third cylinders.

2. A cylindrical rule as set forth in claim 1, wherein said means includes a bevel wheel disposed in said recess and frictionally engaging said second cylinder and a mechanism for rotating said wheel accessible from the free end of said extension.

3. A calculator as set forth in claim 2, wherein said mechanism includes a rod extending through a bore in said another portion which is parallel to the direction of the aligned axes of the cylinders, said rod engaging said bore, one end of said rod secured to said bevel wheel, and another wheel disposed adjacent the other end of the third cylinder, said wheel being secured at its center to the other end of said rod.

References Cited UNITED STATES PATENTS Szenhak 23587 Co1we11 235-795 Sutton 23579.5 Liebmann et a1. 23579.5 X Quillinan 235-70 Adler 23587 Balch 23584 FOREIGN PATENTS France. France. Germany. Germany. Switzerland.

US. Cl. X.R. 

